Feeding means for drills.



lL. C. BAYLES.

FEEDING'MEANS FOR DHILLS. APPucAfloN man APR.A 14. 1911*.

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V:LEWIS c. BAYLEs, OF EASTON, PENNSYLVANIA, AssIGNOE 'ro INGEESoLL-EAND'M COMPANY, OE JERSEY CITY, NEW JERSEY, A CORPORATION or NEW JERSEY.

FEEDING MEANS FOB, DRILELS.

To all whom t may concern:

`Be it known that LLEwrs C. BAYLES, a citizen of the United States', residing at Easton, in the county of Northampton and State of Pennsylvania, have invented a certain new and useful improvement in Feeding Means for Drills, of which the following is a specification,

This invention relates to percussive tools, and in particular tothe means for feeding and holding hammer drills to the work.

The object of this invention is to improve the present means employed for automatically feeding and holding hammer drills to the work and especially that class of hammer drills in which the drilling steel is automatically rotated. y n y In the prior art two methods have been employed to accomplish this.u The most common method of feeding such tools to the work is to attach a feed cylinder and piston to the rear of the power cylinder and by supplying a portion of the actuating fluid to the feed cylinder cause the tool to becon` stantly forcedk against the work. The objection to this method is the inability to use one diameter feed cylinder and piston for varying/conditions. 'IfV the'pressure of the motive iuid is high then a much smaller feed'cylinder'will be required than with low pressure. A feed cylinder of suitable diameter for low pressures'will, if used with high pressure, force the drill steel so hard against its work that the cutting edges of the bit are soon worn away and the bit destroyed. Again, la larger feed cylinder is required when drilling a vertical up hole than a horizontal hole, as' in the former case the feed cylinder must overcome the recoil vplus the weight of the tool. -On down holes the feed Ycylinder only has to overcome the recoil less the weight ofthe tool.

Various designs l'of pressure reducing valves have been tried between the supply and the feed cylinder,-but they all require 'hand adjustment eachk time the conditions change and are, therefore.I not automatic and have provento be unsatisfactory in meeting the varying couditionsof airlpressure, pitch of`pole,etc. The other standard' method of feeding -a hammer drill to the work is what is known as the jump feed. In this 'method the drill carries pawls which engage thejteeth of a stationary rack. When the drilling' steel haspenetratedthe rock a'cerd n Specification of Letters Patent. Pateutd Apr, 8, 1919, `Application filed April 14, 1917. Serial No. 162,025. j i A tain distance the hammer piston strikes the vcylinder front head and drives the entire drill a tooth along the rack where the pawls hold it until the drill steel has penetrated a distance equal to the distance between adjacent teeth on the rack, when the drill is again jumped forward. Y

The objections to this method are thatthe striking of the front head by the piston dam-l ages and destroys the entire machine after a short time and also the fact that a number of blows ofthe piston -are not fully eifective in performing the work of drilling. The result is thatwhen the' full power of the blow is not delivered to the drill steel the drilling speed falls oli. If the compression or cushion betwen the piston and'front cylinder head is increased, the shock to the machine is reduced, but a portion` of the power of the blow is absorbed in the cushion and the drilling speed is reduced.

This' invention is intended to overcome the v above mentioned defects and to combiner in one construction air feeding means and jump feeding means mutually coperating to advance and hold the drill irmlyto the work.

With the above Yand otherobjects in view, I have devised the improvedhammer drill feeding means a practical embodiment 'of which is represented in the accompanying drawings, in which, Y Y

Figure l is a sectional view of a percussive self rotating hammer drill and improved feeding means in place;

Fig. 2 is a plan view of a portionof the drill showing some of the parts, and

Fig. 3 is aV cross sectional view Ltaken on the line 3-3 of Fig. 2.

ln the construction as shown in the drawings, 1 represents the 4bodv of the self rotating percussive tool to which my improved feeding means are attached. This tool may be of any wellknown and common form. the form selected for illustration being of 'the hammer drill tvpe in which a drill steel Extending throughout the length of the rod is a fluid passage 8 which is in communication with the pressure fluid `supply when the throttle valve `9 is in open position. At the lower end of the rod 5 is a pressure tight piston 10 formed by collars 11 and leather cup washers 12 working in a cylinder 13 surrounding the rod 5 so that air admitted to the chamber below the piston 10 through the fluid supply passages 8 will force the body of the drillv upwardly or kiorwardl-y against the work.

and cylinder 13 are of considerable length so that a wide range of drilling is accomplished without changing drill steels. From the description so far it is obvious that an air feeding means has been provided which is ofwell known construction.

s Upon one side of the rod 5, a rack 1l is provided, extending substantially the length of the rod 5 and mounted on the cylindeil 13 preferably at its upper end is a pawl 15 meshing with the rack 14. The pawl 15 may be of any well known form but in the form shown is pro-vided with a plurality of teeth. each meshing with a tooth of the rack in order to impart strength to the Vpawl and to prevent undue wear. The pawl 15 moves "at ain obliqueangle-to the rod 5 sotha't as the pawl 15 engages the rack 14 a slight retrograde movement of the rod 5 and the body of the drill is accomplished which will effectively free the drill vbit from the bottom ofthe hole being drilled and will thus allow the idrirll steel to be easily rotated. In order to yieldiriigly hold the pawl in place a plate spring 16 and vclamping clip 417 are provided.

Iii operatioi'i. when the throttle valve 9 is turned to admit air or other iiuid under pressure from the inlet 18 `vto the cylinder l. to reciprocate the piston 3, the fluid is also admitted to the -air feed cylinder 13. The diameter of the cylinder 13 is somewhat smaller in thepresent invention than in the older types of air feed tools for the reason that in the older forms of air feed toolsl the pressure of the iiuid below the piston 10 in cylinder 13 was depended upon not only to advance the ydrill to the work. but hold it rinly against recoil. In Ithe presen-t invention the feed Ecylinder 13 is 'only of such diameter @that the pressure of the motive fluid below the piston 10 is suiiicient ino carry the .weight of the tool and advance 'the tool,;but not sufficient to prevent the tool -jumpingpback from the work on account of the recoil. The drill after having been advanced to the work and having begun outti'ng soon cuts a chamber in advance ioff the :bit and must be advanced to take up that distance.

yThe feed `cylinder 13 constantly exerts a. forward pressure on the tool, this being suilicien-t to move'the tool forward during the rearward stroke of the piston but not enough rlllie rod to hold it there when the recoil takes place during the forward stroke of the piston. This holding againstbackward movement is accomplished bythe pawl 1'5 and rack 1l. As soon as the forward jump of the tool between blows exceeds the distance between adjacent teeth on the rack 14 the pawl 15 engages :the next set of teeth below lon the rack 14 and thus establishes' a new limit for the backward movement or recoil of the drill slightly above the previous limit.'V j

It will be seen from the abovedescription that `there has been provided a combination of air .and jump feeding device which will not only operate efficiently under all conditions, but will be lighter in weight than the older forms of air feeds :due to its smaller diameter of the feed cylinder and piston and in addition will use less air than previous forms due to the: fact lthat with .the present invention it is possible to use a cylinder 113 somewhat smaller in .diameter vthan in older forms -of air feeding means.

It is .to be understood 'that while the present showing and description disclose only one specific embodiment lof this present in vention, other forms and modifications ,are included within the spirit and scop'ethereof, as expressed in the appended claims.

What I claim is:

1. In a percussive tool having .in combination, air feedingmeans and an :auxiliary feed device comprisingy a rack attached to said percussive tool, and a pawl adapted upon engaging said rack to permit a fslight retrograde movement of said tool relative to said rack.

2. In a combined air and jump feeding means for percussive tools, an air Vfeed Icyilinder provided with a. piston, a rack aittached to said percussive tool extending through said cylinder to said piston provided with an air supply passage for said air feed cylinder, .and a pawl mounted upon said air feed cylinder adapted to yieldingly engage said rack permitting a slight retrograde movement of the tool. l

3. In a combined air and jump feeding device for percussive tools, an air feed cylind-er, a rack within said cylinder, said rack being attached to said percussive tool and provided with an air supply passage lfor said cylinder extending throughout its length and having a feed piston upon its end, and a pawl mounted to slide ololiquely upon the air feed cylinder engaging said rack. f

4. 1n a combined air and jump feeding device for percussive 'tools7 an air feed cylinder, a piston operating within said 'cylinder, a rack attached to said piston atene end and to the percussive tool at its other end and extending` within said cylinder and a pawl mounted to slide yob'lique'ly upon said cylinder :engaging said rack..

5. In a feeding device for percussive tools, a rack attached to said percussive tool, and a pawl mounted obliquely upon a Support for said toolto permit a slight retrograde movement of the tool when the pawl engages a tooth of the rack.

6. In a feed device for percussive tools, in combination, a stationary support, a rack mounted upon the tool and a pawl mounted to slide obliquely in said stationary support for said tool'to permit a slight retrograde movement ofv-the 'tool when the pawl engages a tooth of the rack.

7. A feed device for hammer drills and the like, consisting of a feed cylinder, a feed piston operating therein, a piston rod connected to said feed piston and extending beyond the end f said feed cylinder, a rack on said piston rod, a pawl carried by said feed cylinder to engage Said rack, per1nitting a slight retrograde movement of said rack relative to said feed cylinder after the pawl enters the space between two teeth of the rack and means for supplying motive fluid under pressure to the said feed cylinder below said feed piston.

8. In a feed device for percussive tools, a rack having one end secured to a per- Copies of this patent may be obtained for cussive tool, afeed pistonsecured to. the` said feed cylinder and engaging said rack,

said pawl'aiidrack being so shaped as to lpermit a slight retrograde movement of said rack after the teeth on said rack and pawl engage-and means for supplying fluid under pressure l'to said feed cylinder below said feed piston, substantially as shown and described.

9. In a feed device for percussive tools, a rack having one end rigidly secured to a percussive tool, a feed piston secured t0 the other end of said rack, a feed cylinder surrounding saidfeed piston and said rack, a pawl carried by said feed cylinder and engaging said rack, said pawl being so formed and mounted as to permit a slight retrograde movement of said rack after the teeth on said rack and pawl engage and means for supplying fluid under pressure to said feed cylinder behind said feed piston, substantially as shown and described.

In testimony whereof, I have hereunto sei'l my hand.

LEWIS C. BAYLES.

ve cents each, 'ny addressing the Commissioner of Patents, Washington, D. C.

It is hereby certified that in Letters Patent No. 1,299,814, granted April 8, 1919, upon the application of Lewis C. Bayles, of Easton, Pennsylvania, for an improvement in Feeding Means for Drills, an error appears in the printed speoication requiring correction as follows: Page 2, line 110, claim 2, strike out the Word yieldingly; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 27th day of May, A. D., 1919.

i R. F. WHITEHEAD,

YActing Commissioner of Patents.

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